= ACROCEPHALOSYNDACTYLY type I

[Eugène Charles Apert (1868–1940), médecin des hôpitaux Hôtel-Dieu and at the Hôpital des Enfants-Malades]

Frequency: 5.5÷1,000,000 neonates

Etiology: autosomal dominant with incomplete penetrance; sporadic (in majority)

Associated with CNS anomalies:

• megalocephaly, gyral abnormalities, hypoplastic white matter, heterotopic gray matter, frontal encephalocele, corpus callosal agenesis, Kleeblattschädel, cleft palate, ventriculomegaly (? related to skull base hypoplasia, rarely progressive)

• IQ varies depending on CNS anomalies (in 50% normal)
• otitis media (high prevalence)
• bifid uvula
• conductive hearing loss (common ← external + middle ear malformations)

• Skull
  • downturned mouth
  • brachycephalic skull (← coronal craniosynostosis) + flat occiput
  • widened metopic + sagittal sutures extending from glabella to posterior fontanel (closing between 2–4 years)
  • hypoplastic / retruded midface:
    • hypertelorism
    • shallow orbits with proptosis
    • underdeveloped paranasal sinuses
    • underdeveloped maxilla with prognathism
  • high pointed arch of palate
  • prominent vertical crest in middle of forehead (← increased intracranial pressure)
  • V-shaped anterior fossa ← elevation of lateral margins of lesser sphenoid
  • ± enlargement of sella
  • stylohyoid ligament calcification (38–88%)
  • cervical spine fusion (in up to 71%), commonly of 5^th and 6^th vertebrae
  • choanal stenosis
• Hand & feet
  • severe symmetric syndactyly = fusion of distal portions of phalanges, metacarpals / carpals (most often of 2^nd, 3^rd + 4^th digit)
  • absence of middle phalanges
  • missing / supernumerary carpal / tarsal bones
  • pseudarthroses
• GU (10%)
  • cryptorchidism
  • hydronephrosis
  • polycystic kidneys (rare)
  • bicornuate uterus (rare)